Extraction of citric acid through an emulsion liquid membrane containing Aliquat 336 as carrier

Abstract

The extraction of citric acid from aqueous solutions through an emulsion liquid membrane containing Aliquat 336 carrier was studied. For the emulsions to be functionally stable, it was necessary to select suitable combinations of surfactants and internal stripping reagents. A quaternary amine, trioctylmethylammonium chloride (TOMAC), commercially known as Aliquat 336, was used as a complexing reagent for the extraction of citric acid from aqueous solutions, using sodium carbonate solutions as the internal stripping reagent. A nonionic surfactant, Span 80, was utilized to stabilize the emulsion. A mixture of STA90 NS, dominantly of paraffinic origin, and xylene was used as a diluent. Such parameters that affect the rate of extraction of citric acid, like surfactant concentration, initial feed pH, concentration of feed solution, carrier concentration, and stripping reagent concentration, were examined experimentally. Under the conditions studied, it was found that it is possible to extract about 90% of the acid from the relatively concentrated feed solutions of 10% (w/v).